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At least 1,189 records · Page 66

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NASA NTRS2013

DSP/FPGA Design for a High-Speed Programmable S-Band Space Transceiver

Traditional command uplink receivers are very limited in performance capability, take a long time to acquire, cannot operate on both uplink bands (NASA & AFSCN), and only support low-rate communications. As a result, transceivers end up on many programs critical paths, even though they should be a standard purchased spacecraft subsystem. Also, many missions are impacted by the low effective uplink throughput. In order to tackle these challenges, a transceiver was developed that will provide on-site frequency agility, support of high uplink rates, and operation on both NASA and AFSCN frequency bands. The device is a low-power, high-reliability, and high-performance digital signal processing (DSP) demodulator for an on-orbit programmable command receiver.

Janicik, Jeffrey↗

NASA NTRS2009

The Deep Impact Network Experiment Operations Center

Delay/Disruption Tolerant Networking (DTN) promises solutions in solving space communications challenges arising from disconnections as orbiters lose line-of-sight with landers, long propagation delays over interplanetary links, and other phenomena. DTN has been identified as the basis for the future NASA space communications network backbone, and international standardization is progressing through both the Consultative Committee for Space Data Systems (CCSDS) and the Internet Engineering Task Force (IETF). JPL has developed an implementation of the DTN architecture, called the Interplanetary Overlay Network (ION). ION is specifically implemented for space use, including design for use in a real-time operating system environment and high processing efficiency. In order to raise the Technology Readiness Level of ION, the first deep space flight demonstration of DTN is underway, using the Deep Impact (DI) spacecraft. Called the Deep Impact Network (DINET), operations are planned for Fall 2008. An essential component of the DINET project is the Experiment Operations Center (EOC), which will generate and receive the test communications traffic as well as "out-of-DTN band" command and control of the DTN experiment, store DTN flight test information in a database, provide display systems for monitoring DTN operations status and statistics (e.g., bundle throughput), and support query and analyses of the data collected. This paper describes the DINET EOC and its value in the DTN flight experiment and potential for further DTN testing.

flight experiment↗

NASA NTRS2023

Best Practices for the Design, Development, and Operation of Robust and Reliable Space Vehicle Guidance, Navigation, and Control Systems

This document summarizes and updates the NESC Guidance, Navigation, and Control (GN&C) Technical Discipline Team’s (TDT) work to synthesize and document the current best practices for the design & development of robust and reliable GN&C systems for robotic and crewed (human-rated) spacecraft. These GN&C best practices for future science and exploration missions were derived from the lessons learned, both positive and negative, on earlier spaceflight projects, both robotic and crewed. An attempt has been made to capture preferred practices that reflect the key considerations, trades, and processes directly attributed to past mission success.

Guidance, Navigation, and Control↗

NASA NTRS2022

A Modular Framework for Integrating and Visualizing Telemetry for Mars 2020 Rover Mechanism Operations

The analysis of mechanism telemetry requires a wide variety of tools to quickly and effectively assess spacecraft state, capture long-term trends in system performance, and identify and track anomalous events. Such analysis often requires spacecraft telemetry to first be transformed into derived fields and aggregated statistics before operators can begin their analysis. In past missions, aspects of this process have been automated, but operators were expected to use their own tools and procedures to understand and visualize the data, which led to redundant and inconsistent tools and processes. The Mech Data Tools Python library (MDT) was developed to provide a flexible, unified tool set for operators to extract and analyze mechanism telemetry over the life of the Mars 2020 surface mission. MDT consists of a set of configurable components that implement standard interfaces for ingesting input and producing output. Components can be chained together to form a data processing pipeline. Data are ingested from several sources within the greater Mars 2020 cloud infrastructure and stored in pandas DataFrames, which allows users to leverage the data manipulation capabilities present within the widely-used pandas library. Visualization capabilities are provided through the Plotly library, which generates interactive plots for users to interpret. Following the beginning of Mars 2020 surface operations, usage of MDT has spread to all mechanism-focused subsystems and has demonstrated great utility in analyzing early surface activities. This paper describes MDT’s evolution from heritage mechanism telemetry tools, the critical architecture decisions and challenges faced over MDT’s two years of development, and current applications of MDT in support of mechanism operations.

Wolsieffer, Ben↗

DOE OSTI2011

Seeing the Light (LBNL Science at the Theater)

Berkeley Lab's Science at the Theater event "Seeing the Light" took place on Sept 12, 2011, at Berkeley Repertory's Roda Theatre. Learn how the Advanced Light Source is improving medicine, paving the way for clean energy, changing the future of computers, and much more. Featured speakers are Berkeley Lab's Roger Falcone, Rachel Segalman, Andrew Westphal, and Stanford University's Axel Brunger. Rachel Segalman: The future of clean energy technology relies on a better understanding of materials at the nanoscale. Berkeley Lab's Rachel Segalman uses the ALS to conduct this research, which could lead to improved photovoltaics and fuel cells. Axel Brunger: Improved treatment for human diseases hinges on understanding molecular-scale processes. Stanford University's Axel Brunger will discuss a new melanoma drug that was developed by a local company, Plexxikon, using the ALS for X-ray data collection. Andrew Westphal: What's comet dust made of? Andrew Westphal of UC Berkeley's Space Sciences Laboratory uses the ALS to study comet dust and interplanetary space dust collected by a NASA spacecraft. Moderated by Roger Falcone, Division Director of the Advanced Light Source

36 MATERIALS SCIENCE↗

NASA NTRSDate not supplied

Modeling Spacecraft Power Systems Using the SPACE Code

The NASA Glenn Research Center’s Power Architecture and Analysis Branch performs spacecraft electrical power system (EPS) performance analysis using the System Power Analysis for Capability Evaluation (SPACE) model. Accurately predicting EPS performance requires a wide range of inputs, including the spacecraft’s position, attitude, solar array temperature, load demand, and data on the EPS itself. By operating as a combined analysis tool with integrated orbit mechanics, attitude, shadowing, thermal, solar array, battery, and electrical component models, SPACE provides flexibility for the analyst to examine various scenarios without a time-consuming iterative process involving separate analysis tools and groups. SPACE also achieves short run times by tailoring the complexity of the included models, providing enough fidelity to ensure accurate EPS performance predictions without being bogged down by unnecessary detail. These advantages that SPACE has over similar power system models has contributed to its successful use on a variety of human spaceflight programs for over three decades, and makes it applicable across the development cycle from early conceptual design up through on-orbit operations.

Electrical Power System↗

NASA NTRS2004

Measurement of Global Precipitation

The Global Precipitation Measurement (GPM) Program is an international cooperative effort whose objectives are to (a) obtain increased understanding of rainfall processes, and (b) make frequent rainfall measurements on a global basis. The National Aeronautics and Space Administration (NASA) of the United States and the Japanese Aviation and Exploration Agency (JAXA) have entered into a cooperative agreement for the formulation and development of GPM. This agreement is a continuation of the partnership that developed the highly successful Tropical Rainfall Measuring Mission (TRMM) that was launched in November 1997; this mission continues to provide valuable scientific and meteorological information on rainfall and the associated processes. International collaboration on GPM from other space agencies has been solicited, and discussions regarding their participation are currently in progress. NASA has taken lead responsibility for the planning and formulation of GPM, Key elements of the Program to be provided by NASA include a Core satellite bus instrumented with a multi-channel microwave radiometer, a Ground Validation System and a ground-based Precipitation Processing System (PPS). JAXA will provide a Dual-frequency Precipitation Radar for installation on the Core satellite and launch services. Other United States agencies and international partners may participate in a number of ways, such as providing rainfall measurements obtained from their own national space-borne platforms, providing local rainfall measurements to support the ground validation activities, or providing hardware or launch services for GPM constellation spacecraft. This paper will present an overview of the current planning for the GPM Program, and discuss in more detail the status of the lead author's primary responsibility, development and acquisition of the GPM Microwave Imager.

Flaming, Gilbert Mark↗

NASA NTRS1999

Photochemistry of Pluto's Atmosphere

This work include studies of two problems: (1) Modeling thermal balance, structure. and escape processes in Pluto's upper atmosphere. This study has been completed in full. A new method, of analytic solution for the equation of hydrodynamic flow from in atmosphere been developed. It was found that the ultraviolet absorption by methane which was previously ignored is even more important in Pluto's thermal balance than the extreme ultraviolet absorption by nitrogen. Two basic models of the lower atmosphere have been suggested, with a tropopause and a planetary surface at the bottom of the stellar occultation lightcurve, respectively, Vertical profiles, of temperature, density, gas velocity, and the CH4 mixing ratio have been calculated for these two models at low, mean, and high solar activity (six models). We prove that Pluto' " s atmosphere is restricted to 3060-4500 km, which makes possible a close flyby of future spacecraft. Implication for Pluto's evolution have also been discussed. and (2) Modeling of Pluto's photochemistry. Based on the results of (1), we have made some changes in the basic continuity equation and in the boundary conditions which reflect a unique can of hydrodynamic escape and therefore have not been used in modeling of other planetary atmospheres. We model photochemistry of 44 neutral and 23 ion species. This work required solution of a set of 67 second-order nonlinear ordinary differential equations. Two models have been developed. Each model consists of the vertical profiles for 67 species, their escape and precipitation rates. These models predict the chemical structure and basic chemical processes in the current atmosphere and possible implication of these processes for evolution. This study has also been completed in full.

Krasnopolsky, Vladimir A.↗

NASA NTRS1990

Planetary spacecraft cost modeling utilizing labor estimating relationships

A basic computerized technology is presented for estimating labor hours and cost of unmanned planetary and lunar programs. The user friendly methodology designated Labor Estimating Relationship/Cost Estimating Relationship (LERCER) organizes the forecasting process according to vehicle subsystem levels. The level of input variables required by the model in predicting cost is consistent with pre-Phase A type mission analysis. Twenty one program categories were used in the modeling. To develop the model, numerous LER and CER studies were surveyed and modified when required. The result of the research along with components of the LERCER program are reported.

Williams, Raymond↗

NASA NTRS2005

Advanced Power Regulator Developed for Spacecraft

The majority of new satellites generate electrical power using photovoltaic solar arrays and store energy in batteries for use during eclipse periods. Careful regulation of battery charging during insolation can greatly increase the expected lifetime of the satellite. The battery charge regulator is usually custom designed for each satellite and its specific mission. Economic competition in the small satellite market requires battery charge regulators that are lightweight, efficient, inexpensive, and modular enough to be used in a wide variety of satellites. A new battery charge regulator topology has been developed at the NASA Lewis Research Center to address these needs. The new regulator topology uses industry-standard dc-dc converters and a unique interconnection to provide size, weight, efficiency, fault tolerance, and modularity benefits over existing systems. A transformer-isolated buck converter is connected such that the high input line is connected in series with the output. This "bypass connection" biases the converter's output onto the solar array voltage. Because of this biasing, the converter only processes the fraction of power necessary to charge the battery above the solar array voltage. Likewise, the same converter hookup can be used to regulate the battery output to the spacecraft power bus with similar fractional power processing. The advantages of this scheme are: 1) Because only a fraction of the power is processed through the dc-dc converter, the single- stage conversion efficiency is 94 to 98 percent; 2) Costly, high-efficiency dc-dc converters are not necessary for high end-to-end system efficiency; 3) The system is highly fault tolerant because the bypass connection will still deliver power if the dc-dc converter fails; and 4) The converters can easily be connected in parallel, allowing higher power systems to be built from a common building block. This new technology will be spaceflight tested in the Photovoltaic Regulator Kit Experiment (PRKE) on TRW's Small Spacecraft Technology Initiative (SSTI) satellite scheduled for launch in 1996. This experiment uses commercial dc-dc converters (28 to 15 Vdc) and additional control circuitry to regulate current to a battery load. The 60-W, 87- percent efficiency converters can control 180 W of power at an efficiency of 94 percent in the new configuration. The power density of the Photovoltaic Regulator Kit Experiment is about 200 W/kg.

Source record↗

NASA NTRS1996

Advanced Power Regulator Developed for Spacecraft

Source record↗

DOE OSTI2017

Model of an ion flow and a method for calculating the erosion of discharge-chamber walls in a stationary plasma thruster

Morozov’s stationary plasma thrusters (SPTs) are used effectively in motion-control systems of Russian and foreign spacecraft, and the field of their application is still expanding. For this reason, the demands placed in the output parameters and lifetime of such thrusters are becoming more stringent. When solving the problems of increasing the service lifetime of SPTs, methods for predicting the erosion of discharge-chamber walls–a process that limits the lifetime of a thruster—are useful. We developed one such method earlier, which has been efficiently used in the development of modern SPTs. This letter presents an additional physical grounding and further development of the main ideas of this method on the basis of results obtained in recent years. This grounding makes it possible to expand the range of applicability of the method.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

NASA NTRS1979

CCD sensors for spacecraft optical navigation

The optical navigation process uses spaceborne measurements of the apparent direction vector from the spacecraft to a target body, (planet, satellite, star, etc.) to improve estimates of the spacecraft trajectory. Ground-based controllers assimilate the optical measurements, together with spacecraft radio-tracking data and target ephemeris data, to generate a best estimate of the trajectory relative to the target. The present paper deals with a development program supporting the use of (solid state) CCD (Charged Coupled Device) imagers for spacecraft navigation. It is shown that stars can be detected that are two to three magnitudes fainter than with an equivalent vidicon based instrument, that effects of global response nonuniformity and dark current spikes can be essentially eliminated from the data as a result of the reproducibility of both effects, and that charge trailing during readout of star image data can lead to position measurement errors.

Eisenman, A. R.↗

NASA NTRS1985

A modular docking mechanism for in-orbit assembly and spacecraft servicing

A Docking Mechanism concept is described which is suitable for use with autonomous docking systems. The central feature of using simple cylindrical handles on one side and a type of prism seating on the other is offered as a practical method of achieving a standardized structural interface without freezing continued development of the latches, either technically or commercially. The main emphasis in docking mechanism concepts is in two directions: (1) a very simple docking mechanism, involving mainly the latch mechanism to achieve a structural link; and (2) a sophisticated Docking Mechanism, where the latch mechanism is designed for nonrigid spacecraft and the achievement of very low dynamic interactions between spacecraft during the docking process.

Gampe, F.↗

NASA NTRS1991

Generalized covariance analysis for partially autonomous deep space missions

A new covariance analysis method is presented that is suitable for the evaluation of multiple impulsive controllers acting on some stochastic process x. The method accommodates batch and sequential estimators with equal ease and accounts for time-delay effects in a natural manner. The formalism is developed in terms of a generalized state vector that is formed from the system state vector x, augmented by various fixed epoch estimates, and a data vector formed from discrete time observations of the system. Recursions are developed for time transition, measurement incorporation, and impulsive control updating of the generalized covariance matrix. Means of limiting the dimensional growth of the generalized state vector via the processes of estimator epoch adjustment and measurement vector deflation are described and the application of numerically stable matrix factorization methods to the generalized covariance recursions is outlined. The method is applied to the Magellan spacecraft to demonstrate the capability of ground-based optimal estimation and control of gyro/star scanner misalignment.

Boone, Jack N.↗

NASA NTRS1992

Space Station Freedom - Initial plans for U.S. utilization

NASA's utilization plans for the Space Station Freedom (SSF) are outlined with references to the Consolidated Operations and Utilization Plan (COUP) being developed to cover the first five years of the program. The SSF is described with particular attention given to the spacecraft capabilities, and initial long-term U.S. objectives are set forth with more immediate corresponding research areas. U.S. plans include research in microgravity, life sciences, and technology, and payload concepts are shown to be in development for each area. The SSF is expected to be a useful resource for: (1) commercial research on crystal growth; (2) investigations into physical and chemical processes in the microgravitational environment; and (3) technology studies relevant to the efficient exploitation of space. The NASA Partner Utilization Plan on which these observations are based is being prepared for incorporation into the SSF COUP.

Epstein, Barry↗

NASA NTRS1993

MSFC orbital spacecraft development emphases for this decade

Historically, the Marshall Space Flight Center (MSFC) has been responsible for significant accomplishments in the area of developing both manned and unmanned spacecraft. MSFC is presently involved in many of NASA's largest and most prominent programs, with some operational, others being readied for flight, and still others in various stages of design and development. Examples of MSFC programs being designed or developed are Space Station Freedom (S.S. Freedom), the Advanced X-Ray Astrophysics Facility (AXAF) which includes imaging and spectroscopy facilities, the Laser Atmospheric Wind Sounder (LAWS), and the Lunar Ultraviolet Telescope Experiment (LUTE), with Spacelab and Tethered Satellite System (TSS) as examples of current operational MSFC spacecraft. The information obtained from the Long Duration Exposure Facility (LDEF) will aid the design process and life predictions for these and all future spacecraft. A second LDEF is presently being considered. All of these projects will be briefly described in this paper.

Schwinghamer, Robert J.↗

NASA NTRS1997

Optical Sensors Based on Single Arm Thin Film Waveguide Interferometer

All the goals of the research effort for the first year were met by the accomplishments. Additional efforts were done to speed up the process of development and construction of the experimental gas chamber which will be completed by the end of 1997. This chamber incorporates vacuum sealed multimode optical fiber lines which connect the sensor to the remote light source and signal processing equipment. This optical fiber line is a prototype of actual optical communication links connecting real sensors to a control unit within an aircraft or spacecraft. An important problem which we are planning to focus on during the second year is coupling of optical fiber line to the sensor. Currently this problem is solved using focusing optics and prism couplers. More reliable solutions are planned to be investigated.

Sarkisov, Sergey S.↗